The simple answer is that most wasps are beneficial, and generally not aggressive. Yellowjackets, are often mistaken for bees and wasps, and are the aggressive and nuisance insects, often mistaken as "bees", that ruin picnics and barbeques. The key is to identify whether that yellow and black flying insect is a honeybee or other type of bee, a wasp, a hornet or a yellow jacket. Download a couple of great article on this topic.

If it looks like this, then it is a yellowjacket. Notice the wide abdomen, the complete lack of respect for your personal space, and the fact that it will gladly taste your meal, your soft drink, or your beer for you.

But, if it looks like this it is a mud dauber, (the main predator --READ eater-- of Black widow spiders), and a friend of your garden;

Or, if it looks like this, it is a paper wasp (would much rather eat aphids than your lunch) but has the unseemly habit of building its homes under your nice and dry eaves;

And even if it looks like this , a bald-faced hornet, who much prefer to eat eat pesky insects, including caterpillars, that damage gardens and fruit trees, houseflies and blowflies. You can read a short kid's article here. But, if you are intent on upsetting their home, , they will surely lose their temper. Who wouldn't?

Now, the most important thing to remember here, is that NONE OF THESE INSECTS ARE BEES! The little furry friends to which this site is dedicated look unlike any of their vespid counterparts.